Summary

The spring bloom of phytoplankton—an annual population explosion that propagates poleward across much of the open ocean and spills across the continental shelves—is a seasonal bounty for the marine ecosystem. As it wanes, its annual legacy is a flux of carbon out of the atmosphere as the organic material, containing newly fixed carbon, sinks. On page 54 of this issue, Mahadevan et al. (1) suggest that the bloom can be triggered by instabilities in surface currents that trap phytoplankton near the sunlit surface. In another study, Teeling et al. (2) recently suggested that the bloom itself may help to explain the “paradox of the plankton” (3); how can a seemingly homogeneous ocean sustain thousands of species?